Lighting device for vehicles

ABSTRACT

A lighting device for vehicles with an elongated light guide comprising an end face for the coupling-in of light, into which a light beam radiated from a light source can be coupled-in. The lighting device further comprises elements for the coupling-out of light for the deflection of the coupled-in light beam in the direction of a front skin surface of the elongated light guide, on which the light beam can be coupled-out for the generation of a given light function, such that the front skin surface of the elongated light guide is connected to a rear skin surface by means of a curved dispersion surface. At least one light directing element is arranged between a row of light sources and the light guide so that the light of the light sources arranged in a row can be coupled into the rear skin surface or the curved dispersion surface of the light guide.

CROSS REFERENCE

This application claims priority to U.S. Utility application Ser. No.15/441,309, filed Feb. 24, 2017, which claims priority to U.S. Utilityapplication Ser. No. 14/261,282, filed Apr. 24, 2014, which claimspriority to and the benefit of German Patent Application No. 10 2013104174.4 filed Apr. 25, 2013. The entire disclosures of U.S. Utilityapplication Ser. No. 15/441,309, U.S. Utility application Ser. No.14/261,282, and German Patent Application No. 10 2013 104174.4 arehereby incorporated herein by reference.

TECHNICAL DESCRIPTION OF THE INVENTION

The invention relates to a lighting device for vehicles with anelongated light guide having a end face for the coupling-in of light,into which a light beam radiated from a light source can be coupled-in,and comprising elements for the coupling-out of light for the deflectionof the coupled-in light beam in the direction of a front skin surface ofthe elongated light guide, on which the light beam can be coupled-outfor the generation of a given light function, that the front skinsurface of the elongated light guide is connected to a rear skin surfaceby means of a curved dispersion surface.

From DE 10 2008 038 668 A1, a lighting device for vehicles is known,which comprises an elongated light guide. On a rear skin surface, thislight guide has elements for the coupling-out of light, by means ofwhich light coupled into the light guide and guided by it is deflectedin the direction of a front skin surface and coupled-out of it for thecreation of a given light function. The coupling-in of light is achievedby means of a light source arranged on the end face of the elongatedlight guide. Therefore, the lighting device allows a line-shapedcoupling-out of light, which can for example be used for a directionindicator function. Usually, the light function is accomplished byswitching on the light source on the end face, which results in aninstant light effect over the entire length of the light guide. Thereare endeavors to relax the legal requirements relating to the lightfunctions so that the light guide can provide a sequential lightradiation in the shape of a wandering light function or a running lightfunction. By this means, the light function of a “wiping” directionindicator can for example be created. This wandering light function canfor example be effected by means of the sequential switching-on of lightsources arranged in rows, each of which has a separate light guideelement arranged in front. If the elongated light guide was segmented ordivided into in separate segments, each of which with a light sourceassigned to it, the light guide would, however, loose the character of acontinuous appearance with a homogeneous illumination.

SUMMARY OF THE INVENTION

It is therefore the task of the present invention to further develop alighting device so that an elongated light guide can be employed in asimple and compact manner for use in a light function in which thelighting of the light guide changes locally in the longitudinaldirection of the same while maintaining a continuous appearance of thelight guide.

To solve this problem the invention in connection with the preamble ofpatent claim 1 is characterized in that between a row of light sourcesand the light guide, a light directing element is arranged so that lightfrom the light sources arranged in a row can be coupled into the rearskin surface or the curved dispersion surface of the light guide.

The particular advantage of the invention is that by means of anelongated light directing element being assigned to an elongated lightguide, additional light which can be used for a locally variablelighting of the light guide can be supplied to the elongated light guidein a simple manner. By this means, a wandering light function resp. awiping direction indicator function can be created, in which theelongated light guide is lit by and by, resp. sequentially from one endface to the opposite end face. The second light beam deflected by theelongated light directing element is supplied in a directed manner to acurved dispersion surface of the elongated light guide, by which it isdeflected so that it exits at the front skin surface of the light guide.

According to a preferred embodiment of the invention, the elongatedlight directing element runs parallel to the light guide so that thesecond light beam hits exclusively the curved dispersion surface of theelongated light guide. Advantageously, this ensures a definedcoupling-in of light from one longitudinal side into the light guide.

According to an embodiment of the invention, the light guide has atrumpet-shaped and symmetrical embodiment, wherein identically formed,curved dispersion surfaces are provided on opposite sides.Advantageously, this allows particularly a dispersion running verticalto the longitudinal mean plane of the light guide.

According to a further development of the invention, the light sourcesassigned to the light directing element can be switched on and/or offsequentially, so that a locally variable lighting of the light guide isensured in the longitudinal direction of the same. By this means, thelight sources arranged in a row can be switched on one after the other,preferably from an inside of the vehicle toward the outside of thevehicle, until the light guide is lit over its entire length, to createa “wiping direction indicator function”. Then the light source arrangedon the end face of the light guide is switched on, so that theilluminance of the light guide increases instantly over its entirelength. If necessary, the light sources assigned to the light directingelement can then be switched off simultaneously. Should the lightfunction be a direction indicator function, the light source assigned tothe light guide is switched off after a given time interval and theprocess can start again. Should the light function be e.g. a tail light,the corresponding light sources remain in the activated condition untilthe light function is switched off.

According to a further development of the invention, the light directingelement is embodied so that the second light beam coupled-in via thecurved dispersion surface has the same dispersion as a first light beam,which is coupled into the light guide on the end face and which isdeflected via elements for the coupling-out of light of the same in thedirection of the front skin surface. Advantageously, the first lightbeam and the second light beam have therefore the same dispersioneffect, particularly across the longitudinal mean plane of the lightguide.

According to a further development of the invention, the light directingelement is embodied as a reflector having reflector surfaces extendinginto the vicinity of the dispersion surface. If necessary, the reflectorcan comprise additional inner reflector surfaces to ensure an improvedlight output for the coupling-in of the same into the light guide.

According to a further variant of the invention, the light directingelement is embodied as a light guide element being arranged as a solidbody between the rows of light sources and the light guide. The secondlight beam being coupled into the light guide element is deflected bymeans of total reflection on the lateral surfaces of the light guideelement toward the light guide.

Preferably, the light guide element has a jaw-shaped embodiment, whereinthe second light beam is essentially radiated into an end region of thetwo jaws of the light guide element in the direction of the dispersionsurface.

These aspects are merely illustrative of the innumerable aspectsassociated with the present invention and should not be deemed aslimiting in any manner. These and other aspects, features and advantagesof the present invention will become apparent from the followingdetailed description when taken in conjunction with the referenceddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is now made more particularly to the drawings, whichillustrate the best presently known mode of carrying out the inventionand wherein similar reference characters indicate the same partsthroughout the views.

FIG. 1: a schematic lateral view of a lighting device according to afirst embodiment of the invention with a light guide element embodied asa reflector,

FIG. 2: a schematic lateral view of a lighting device according to FIG.1 with an alternative light source arrangement according to a secondembodiment,

FIG. 3: a perspective representation of the lighting device according toFIG. 2 without representation of a light guide,

FIG. 4: a perspective representation of the lighting device according toFIG. 2 with the light guide shown,

FIG. 5: a lateral view of a lighting device according to a thirdembodiment with a light directing element embodied as a light guideelement,

FIG. 6: a schematic representation of the switching process of theadditional light sources arranged in a row in the longitudinal directionof the light guide,

FIG. 7: a lateral view of the lighting device according to a furtherembodiment with an intermediate lens,

FIG. 8: a top view of the embodiment according to FIG. 7,

FIG. 9: a top view of an embodiment with a light directing element whichis continuous in the longitudinal direction,

FIG. 10: a top view of a light directing element having slots,

FIG. 11: a top view of a light directing element having closed slots,

FIG. 12: a lateral view of a light directing element with directedsurface for the coupling-out of light.

FIG. 13: a lateral view of the light directing element with prism-shapedsurface for the coupling-out of light.

FIG. 14: a lateral view of the light directing element withpillow-shaped optic elements on the surface for the coupling-out oflight,

FIG. 15: a lateral view of the light directing element with an etchedsurface for the coupling-out of light,

FIG. 16: a lateral view of a light directing element with a coupling-inoptics according to a first embodiment,

FIG. 17: a lateral view of a light directing element with a coupling-inoptics according to a second embodiment,

FIG. 18: a lateral view of a light directing element with a coupling-inoptics according to a third embodiment,

FIG. 19: a lateral view of a light directing element with a coupling-inoptics according to a fourth embodiment, and

FIG. 20: a lateral view of a lighting device with two light directingelements.

DETAILED DESCRIPTION

In the following detailed description numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those skilled in the art that thepresent invention may be practiced without these specific details. Forexample, the invention is not limited in scope to the particular type ofindustry application depicted in the figures. In other instances,well-known methods, procedures, and components have not been describedin detail so as not to obscure the present invention.

A lighting device for vehicles is arranged in a tail or front region ofa vehicle. The lighting device can be used for the creation of a lightfunction, in which the light can be changeably radiated with regard toplace and/or time.

According to a first embodiment following FIG. 1, the lighting devicehas an elongated light guide 1 to the rear of which, with regard to themain radiation direction H, a light directing element embodied as areflector 2 is assigned. The reflector 2, like the light guide 1, has anelongated embodiment and extends preferably in a horizontal direction inparallel to the same. A row of light sources 3 is arranged spacedrelative to one another in the longitudinal direction of the reflector 2on a back of the reflector 2 facing away from the light guide 1.

The cross section of the light guide 1 is trumpet-shaped and has a rearskin surface 4, a front skin surface 5, as well as a curved dispersionsurface 6, 6′ connecting the rear skin surface 4 with the front skinsurface 5. The reflector 2 is symmetrically arranged relative to alongitudinal mean plane M of the light guide 1, wherein the identicallyshaped dispersion surfaces 6, 6′ facing one another connect the narrowrear skin surface 4 having a plane embodiment with the front skinsurface 5 having a cylindrical embodiment. On an end face of the lightguide 1 which is not represented, a light source is arranged, whichradiates a first light beam L1 into the light guide, which is coupled-inat a end face of the light guide 1 and is directed onto the skinsurfaces 4, 5, 6, 6′ of the light guide 1 in the longitudinal directionE of the same.

The rear skin surface 4 has prism-shaped optic elements as elements forthe coupling-out of light 7, by means of which the light beams L1hitting them are deflected in the direction of the front skin surface 5.These light beams L1 are then coupled-out on the front skin surface 5for the creation of the light function.

The embodiment of the reflector 2 is preferably symmetrical relative tothe longitudinal mean plane M and has outer reflector surfaces 2′ andinner reflector surfaces 2″. The opposing outer reflector surfaces 2′extend into a region in the vicinity of the curved dispersion surface 6resp. 6′, so that light beams L2 radiated from the light sources 3 arecoupled into the curved dispersion surfaces 6, 6′ in the light guide 1.The inner reflector surface 2″ extends in a region close to thelongitudinal mean plane M so that light beams L2′ (partial light beams)are reflected in direction of the outer reflector surface 2′. The innerreflector surfaces 2″ preferably converge in the longitudinal mean planeM, so that no light L2 radiated from the light sources 3 can directlyhit the rear skin surface 4 and/ or the curved dispersion surfaces 6,6′. The light beams L2 exclusively hit the curved dispersion surfaces 6,6′ once they have been deflected once or several times on the outerreflector surface 2′.

Once the light beam L2 has entered the light guide 1, it is deflected bymeans of the curved dispersion surface 6, 6′ so that it is coupled outon the front skin surface 5 in the main radiation direction H. Herein,the dispersion of the second light beam L2 preferably has the samedispersion as the first light beam L1. The light dispersion,particularly in the vertical direction, is therefore identical.

The reflector surfaces 2′, 2″ can have a smooth surface or an opticalstructure. The optical structure can for example be embodied as pillowoptics or striped optic elements. Alternatively, the optical structurecan also be achieved by means of erosion or etching or lasering.

The reflector 2 can be fastened in a carrier element or a bezel of thelighting device in which the light guide 1 is held.

According to the first embodiment corresponding to FIG. 1 the lightsources 3 are embodied as LED light sources being arranged on a commonrigid carrier plate 8.

According to a second embodiment of the invention corresponding to FIGS.2 to 4, and in contrast to the first embodiment, a row oflateral-LED-light sources 3′ can be assigned to the reflector 2. Incontrast to the first embodiment, these are not arranged on a printedcircuit board running vertical to the longitudinal mean plane M, but ona printed circuit board 8′ running parallel to the longitudinal meanplane M, resp. parallel to the main radiation direction H.

Identical components resp. identical component functions of theexemplary embodiments are marked with identical reference signs.

According to a represented alternative embodiment, the light sources canalso be embodied as OLED light sources, in which the light beam L2 isnot radiated in a punctiform manner, as described in the aboveembodiments, but from a lighting panel.

According to a further embodiment of the invention according to FIG. 5,the light directing element can be embodied as a light guide element 12extending as a solid body between the row of light sources 3′ and thelight guide 1. The light guide element 12 has a jaw-shaped cross-sectionand has two light guide legs 12′, 12″ extending on both sides of thelongitudinal mean plane M. The front ends of the light guide legs 12′,12″ extend into a region in the vicinity of the curved dispersionsurface 6, 6′. The two light guide legs 12′, 12″ each have outer lateralsurfaces 13 and inner lateral surfaces 14, on which the coupled-in lightbeam L2 can be fully reflected. In a free end region of the light guidelegs 12′, 12″ the light beams L2 are coupled-out on the inner lateralsurfaces 14, so that they can enter the light guide 1 through the curveddispersion surfaces 6, 6′. Subsequently a deflection, already describedabove, occurs inside the light guide 1, so that they are coupled-out onthe front skin surface 5 in the main radiation direction H in anidentical manner.

To switch the lighting device on, the light sources 3, 3′ aresequentially switched on by means of a control device which is notrepresented, starting preferably from an innermost side of the vehicletoward an outermost side of the vehicle. By this means, light L2 is, byand by, coupled into the light guide 1 in the longitudinal direction Eby means of the light directing element 2, 12 and radiated from itsfront skin surface 5. This results in a wandering light function resp. alight strip which is extended by and by along the longitudinal directionE of the light guide 1. A wiping effect is created, which can forexample be used when a direction indicator function, a tail lightfunction or a daytime running light function is switched on.

FIG. 6 gives a schematic representation of the light radiated from thelight guide 1 in the longitudinal direction E against the switchingpoints. At the beginning SLC-8468920-1 of the switching process, a lightsource 3, 3′ preferably facing the vehicle inside is switched on at thepoint in time t₀, so that a light radiation L2 is effected in thelongitudinal direction E across a first partial section E1 of the lightguide 1. At the end of a time interval Δt, the neighboring light source3, 3′ is switched on in addition, so that an illumination of the lightguide 1 across a partial section E2 being larger than the partialsection E1 is effected. Subsequently, further light sources 3, 3′ areswitched on sequentially in addition at time intervals of Δt, until thelight guide 1 is lit across its entire extension. The light guide 1 thenradiates the light L2 provided by the light directing element 2, 12across its entire length. The process of switching on the light sources3, 3′ is thus completed. Subsequently, the first light beam L1 of thelight source situated on the front-side surface for the coupling-in oflight of the light guide 1 can be radiated via the front skin surface 5in addition by switching it on, so that an increase in illuminance iscreated across the entire length of the light guide 1. Either the lightsources 3, 3′ assigned to the light directing elements 2, 12 can remainswitched on or they are switched off so that the light guide 1 isilluminated exclusively by the first light beam L1.

For the creation of the direction indicator function, the light sources3, 3′ assigned to the light directing element 2, 12 as well as the lightsources assigned to the light guide 1 are switched off simultaneouslyafter the lapse of a given time interval, so that after a given pause,the described switching process can start again. The switching on of thelighting device therefore effects the creation of a light stripextending in the longitudinal direction, the light strip beingdetermined by the extension of the light guide 1.

The light guide 1 and the light directing element 2, 12 may have astraight or a curved shape.

The light sources 3, 3′ have main axes A, which run in the mainradiation direction H resp. vertically to the longitudinal direction Eof the light guide 1 resp. the light directing element 2, 12. The lightsources 6, 6′ are preferably arranged at identical distances. The lightsource assigned to the light guide 1 being arranged on the end face forthe coupling-in of light of the same has a main axis running vertical tothe main radiation direction H resp. in the direction of thelongitudinal direction E of the light guide 1, if the light guide 1 hasa straight shape. If the light guide 1 has a curved shape, the main axisof this light source is preferably arranged in the direction of a normalof the surface for the coupling-in of light at the end face of the lightguide 1.

According to a further embodiment of the invention according to theFIGS. 7 and 8, a light directing element arranged between the row oflight sources 6 and the light guide 1 can be embodied as an essentiallycuboidal light guide element 22 and followed by an intermediate lens 22′arranged in the same main radiation direction H. The light guide element22 is segmented and has narrow sides 23, 23′ facing away from eachother. Parallel to the longitudinal mean plane M of the light guide 1,the light guide element 22 is limited by opposing flat sides 24, 24′. Ona front side facing the light guide 1, the light guide elements 22 areeach monolithically connected with the continuous intermediate lens 22′in the longitudinal direction E. The intermediate lens 22′ has a contour25 following the course of the light guide 1, on which the light L2 iscoupled-out in the direction of the rear skin surface 4 of the lightguide 1. In this execution of the invention, the light beam L2 isexclusively coupled-in on the rear skin surface 4 of the light guide 1.The rear skin surface 4 has preferably a prism-shaped structure ascoupling-out elements, which on one hand allows a deflection of thelight L1 coupled-in in the longitudinal direction E of the light guide 1toward the front skin surface 5, and on the other hand allows anentrance of the second light beam L2.

According to a further embodiment of the invention according to FIG. 9,a light guide element 26 can be embodied continuously in thelongitudinal direction E. Optionally, the intermediate lens 22′ can beomitted.

According to a further embodiment of the invention according to FIG. 10,a light guide element 27 can have slots 28 having a depth t1 beingsmaller than a depth t2 of the monolithically embodied light element 27.The slots 28 extend from a side on which the light is coupled-in of thelight directing element 27 in the direction of a side for thecoupling-out of light of the same without it being reached. The lightguide segments 27′ separated in this manner are each assigned to a lightsource 3.

According to a further embodiment of the invention according to FIG. 11,a light guide element 29 can be provided, which has closed slots 30 incontrast to the light guide elements 27 according to FIG. 10.

On a side for the coupling-out of light facing the light guide 1, alight guide element 31 can have a directed optic structure 32, forexample a Fresnel structure.

Alternatively, a light guide element 33 can also have a prism-shapedstructure 34 on the side for the coupling-out of light. Alternatively, alight guide element 35 can also have an optical structure provided withpillow-optics elements 36 on the side for the coupling-out of light.Alternatively, a light guide element 37 can also have an etched orlacquered structure 38 on the side for the coupling-out of light.

According to a variant of the invention, a light guide element 39 canhave a concave depression 40 on a side for the coupling-in of light.According to a further alternative according to FIG. 17, a light guideelement 41 can be embodied tapered in the direction of the side for thecoupling-in of light, wherein a depression 42 is assigned to the LEDlight source 3. Depending on the installation space, the LED lightsource 3 can also be arranged at an angle, for example 45 degrees,relative to a longitudinal direction of a light guide element 43. Tothis end, the light guide element 43 has a lateral depression 44 on theside for the coupling-in of light. According to a further embodiment ofthe invention according to FIG. 19, the light source 3 can also bearranged at a right angle relative to the longitudinal direction of alight guide element 45. The light guide element 45 has a deflecting nose46 comprising a refection surface 47, on which the light L2 coupled-invia a depression 48 is deflected in the longitudinal direction of thelight guide element 45.

According to a further embodiment of the invention according to FIG. 20,plate-shaped light guide elements 46, 46′ are arranged on both sides ofthe mean plane M of the light guide 1, each of which has a row of lightsources 3 assigned on a side for the coupling-in of light. The lightguide elements 46, 46′ each have a curved surface for the coupling-outof the light 47, 47′ on the side for the coupling-out of light,following the contour of the curved dispersion surface 6, 6′ of thelight guide. Preferably, there is a constant distance b between thecontour of the surface for the coupling-out of light 47, 47′ on one handand the curved dispersion surface 6, 6′ on the other hand.

LIST OF REFERENCE SIGNS

1 Light guide

2, 2′, 2″ reflector external, internal

3, 3′ Light source

4 Rear skin surface

5 Front skin surface

6, 6′ Curved dispersion surface

7 Elements for the coupling-out of light

8, 8′ Carrier plate

9

10

11

12, 12′, 12″ Light guide legs

13 Outer lateral surfaces

14 Inner lateral surfaces

22, 22′ Light guide element/intermediate lens

23, 23′ Narrow sides

24, 24′ Flat sides

25 Contour

26 Light guide element

27 Light guide element

28 Slots

29 Light guide element

30 Slot

31 Light guide element

A Axis

H Main radiation direction

M Longitudinal mean plane

E Longitudinal direction

L1, L2 Light beam

What is claimed is:
 1. A lighting device for vehicles comprising: anelongated light guide including: an end face for the coupling-in oflight, into which a light beam radiated from a light source can becoupled-in, and elements for the coupling-out of light for thedeflection of the coupled-in light beam in the direction of a front skinsurface of the elongated light guide, on which the light beam can becoupled-out for the generation of a given light function, a curveddispersion surface connecting the front skin surface of the elongatedlight guide to a rear skin surface of the elongated light guide, and atleast one light directing element located between a row of light sourcesand the light guide so that light from the light sources arranged in arow can be coupled into the rear skin surface of the light guide, andwherein the at least one light directing element is embodied as acuboidal light guide element extending between the row of light sourcesand the elongated light guide.
 2. The lighting device according to claim1, wherein the light sources assigned to the elongated light directingelement can be sequentially switched on or off for the creation of anillumination which is locally changeable in the longitudinal directionof the light guide.
 3. The lighting device according to claim 1, whereina second light beam coupled into a surface for the coupling-in of lightof the light guide element facing the light sources can be deflected indirection of the light guide by means of total reflection on the lateralsurfaces of the light guide element.
 4. The lighting device according toclaim 1, wherein the light directing element is segmented in thelongitudinal direction.
 5. The lighting device according to claim 1,wherein the light directing element is continuous in the longitudinaldirection.
 6. The lighting device according to claim 1, wherein thelight directing element has open slots or closed slots on the sidefacing the row of light sources.
 7. The lighting device according toclaim 1, wherein on both sides of a median plane of the light guide,there are light directing elements arranged, each of which has a row oflight sources assigned on a surface for the coupling-in of light facingaway from the light guide and each of which has, on the side for thecoupling out of light facng the light guide, a surface for thecoupling-out of light following the contour of the curved dispersionsurface of the light guide.
 8. The lighting device according to claim 1,wherein an intermediate lens is positioned and located between the lightguide element and the elongated light guide.
 9. The lighting deviceaccording to claim 8, wherein the intermediate lens is cuboidal.
 10. Thelighting device according to claim 8, wherein the intermediate lensabuts the light guide element.